Epitope, Inc. has developed a series of monoclonal antibodies to the gene-products of the HIV, the etiological agent of AIDS. This array of antibodies react with distinct gag, env, and pol-derived proteins. At least two of these monoclonal reagents detect HIV antigens of the surface of a circulatory lymphocyte subpopulation (T4 cells) from AIDS, ARC, and asymptomatic seropositive patients, but not seronegative individuals. Using flow cytometry, a direct test for the AIDS virus has been developed and evaluated in a blinded clinical trial. We now propose (1) to evaluate additional monoclonal antibodies for detection of HIV proteins on cells and in body fluids, (2) to conduct an extensive clinical trial to compare the flow cytometry test with a slide test, and (3) to conduct a longitudinal study to follow seroconversion of high risk clients.